Shore crabs

Code OX619999

Crabs are decapod crustaceans in which the abdomen is reduced and tightly folded under the cephalothorax. The rostrum is reduced and the tail fan is absent.

Grapsidae are squarish crabs with the anterior margin of the carapace approximately straight and the lateral margins with one or more prominent, forward-pointing teeth.

This is the most commonly-met family of shore-dwelling crabs, and many species occur in estuaries, mangroves, or other marginal habitats. The family is not generally considered to occur in strictly inland waters. However, there are reports of Leptograpsodes octodentatus living in freshwater unconnected to the sea at several locations in southern Australia (Abrolhos Islands to Bass Strait islands) and mangrove crabs (Sesarma spp.) also occur in estuaries and mangroves quite far from the open shore.

The main reason for having included Grapsidae in this key is to distinguish this family from true freshwater crabs of the family Sundatelphusidae.

References:

Horwitz, P. (1995) A Preliminary Key to the species of Decapoda (Crustacea: Malacostraca) found in Australian Inland Waters. Co-operative Research Centre for Freshwater Ecology Identification Guide No. 5., Albury, NSW.

Horwitz, P., Knott, B. and Williams, W.D. (1995) A Preliminary Key to the Malacostracan Families (Crustacea) found in Australian Inland Waters. Co-operative Research Centre for Freshwater Ecology Identification Guide No. 4., Albury, NSW.